1. Field of the Disclosure
The present disclosure relates to a display device, and more particularly, to a display device with an integrated touch screen and a method of driving the same.
2. Discussion of the Related Art
Recently, the demand for display devices with an integrated in-cell type touch screen, which include a plurality of built-in elements configuring the touch screen for slimming portable terminals such as smart phones and tablet personal computers (PCs), is increasing.
In a related art display device with an integrated in-cell type touch screen, a plurality of common electrodes for display are segmented into a plurality of touch driving areas and touch sensing areas, thereby allowing a mutual capacitance to be generated between the touch driving area and the touch sensing area. Therefore, the related art display device measures the change of a mutual capacitance that occurs in touch, and thus determines whether there is a touch.
In a related art in-cell type mutual capacitive touch screen using the existing common electrodes, a scheme that uses a plurality of driving electrodes and sensing electrodes necessary for touch driving temporally separates a display driving mode session and a touch driving mode session by using a common electrode, and thus prevents a noise ingredient (which occurs in the display driving mode session) from affecting the touch driving.
When a gate driver for an in-cell type mutual capacitive touch screen using the existing common electrode is provided in a gate-in-panel (GIP) structure, two pull-down transistors are used for applying a gate low voltage (VGL) to a gate electrode during a touch driving mode and most of a display driving mode.
The two pull-down transistors are configured with different transistor elements, and alternately operate in units of a multiple of a frame. A time, at which the two pull-down transistors start the alternation of operations, is a time at which display is started, and moreover, a time at which the two pull-down transistors start the alternation of next operations is a time at which display is started after a certain frame. Therefore, in a certain frame, when one pull-down transistor operates during the display driving mode, the same pull-down transistor also operates during a touch driving mode that is performed later, and the two pull-down transistors alternately operate in units of a multiple of a frame during the touch driving mode.
However, the two pull-down transistors alternately operate during the touch driving mode, and, due to characteristic differences between elements, the two pull-down transistors affect the amount of electrical charges that are generated between a gate electrode and a sensing electrode, causing the shaking of a touch signal.